<!DOCTYPE html>
<html lang="en">

<head>
    <meta charset="UTF-8">
    <meta name="viewport" content="width=device-width, initial-scale=1.0">
    <title>Document</title>
</head>

<body>
    <button id="btn">显示/隐藏</button>
    <div id="box">hello jack</div>
    <script>
        const btn = document.getElementById('btn');
        const box = document.getElementById('box');

        btn.onclick = function () {
            if (box.style.display === 'none') {
                box.style.display = '';
            } else {
                box.style.display = 'none';
            }
            // box.style.display = 'none';
        }
        // btn.onclick = function () {
        //     if (box.hidden === true) {
        //         box.hidden = false;
        //     } else {
        //         box.hidden = true;
        //     }
        // }

    </script>
</body>

</html>